Association of Changes in Diet Quality with Total and Cause-Specific Mortality.

From the Departments of Nutrition (M.S.-P., S.N.B., J.M., T.T.F., Y.L., W.C.W., E.B.R., F.B.H.) and Epidemiology (W.C.W., E.B.R., F.B.H.), Harvard T.H. Chan School of Public Health, Channing Division of Network Medicine, Department of Medicine, Brigham and Women's Hospital and Harvard Medical School (S.N.B., W.C.W., E.B.R., F.B.H.), and Simmons College (T.T.F.) - all in Boston; the Division of Food and Nutrition Sciences, School of Applied Health Sciences and Wellness, Ohio University, Athens (M.S.-P.); and the Department of Epidemiology and Biostatistics and Ministry of Education Key Laboratory of Environment and Health, School of Public Health, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China (A.P.).

Abstract

BACKGROUND:

Few studies have evaluated the relationship between changes in diet quality over time and the risk of death.

METHODS:

We used Cox proportional-hazards models to calculate adjusted hazard ratios for total and cause-specific mortality among 47,994 women in the Nurses' Health Study and 25,745 men in the Health Professionals Follow-up Study from 1998 through 2010. Changes in diet quality over the preceding 12 years (1986-1998) were assessed with the use of the Alternate Healthy Eating Index-2010 score, the Alternate Mediterranean Diet score, and the Dietary Approaches to Stop Hypertension (DASH) diet score.

RESULTS:

The pooled hazard ratios for all-cause mortality among participants who had the greatest improvement in diet quality (13 to 33% improvement), as compared with those who had a relatively stable diet quality (0 to 3% improvement), in the 12-year period were the following: 0.91 (95% confidence interval [CI], 0.85 to 0.97) according to changes in the Alternate Healthy Eating Index score, 0.84 (95 CI%, 0.78 to 0.91) according to changes in the Alternate Mediterranean Diet score, and 0.89 (95% CI, 0.84 to 0.95) according to changes in the DASH score. A 20-percentile increase in diet scores (indicating an improved quality of diet) was significantly associated with a reduction in total mortality of 8 to 17% with the use of the three diet indexes and a 7 to 15% reduction in the risk of death from cardiovascular disease with the use of the Alternate Healthy Eating Index and Alternate Mediterranean Diet. Among participants who maintained a high-quality diet over a 12-year period, the risk of death from any cause was significantly lower - by 14% (95% CI, 8 to 19) when assessed with the Alternate Healthy Eating Index score, 11% (95% CI, 5 to 18) when assessed with the Alternate Mediterranean Diet score, and 9% (95% CI, 2 to 15) when assessed with the DASH score - than the risk among participants with consistently low diet scores over time.

CONCLUSIONS:

Improved diet quality over 12 years was consistently associated with a decreased risk of death. (Funded by the National Institutes of Health.).

Risk of Death from Any Cause, According to Scores on Three Measures of Diet Quality at Baseline and 12 Years Later

The multivariable-adjusted risk of death from any cause according to the Alternate Healthy Eating Index–2010 score (Panel A), the Alternate Mediterranean Diet score (Panel B), and the Dietary Approaches to Stop Hypertension (DASH) score (Panel C) at baseline and 12 years later is shown. Baseline scores are shown as low, medium, and high, with higher scores indicating a healthier diet. At 12 years, a participant may have had a consistently low score over time, a change from a low score to a medium or high score, a consistently medium score over time, a change from a medium score to a low or high score, a consistently high score over time, or a change from a high score to a low or medium score. The reference group (hazard ratio, 1.00) was the low score at both baseline and the 12-year follow-up period. Results of the Nurses’ Health Study and the Health Professionals Follow-up Study were combined with the use of the fixed-effects model. I bars represent 95% confidence intervals. Asterisks indicate P<0.05.

Risk of Death from Any Cause per 20-Percentile Increase in Diet-Quality Scores

The multivariable-adjusted risk of death from any cause per 20-percentile increase in the score (indicating improvement in the quality of the diet) on three measures of diet quality is shown. The 20-percentile increase in each score was calculated from the median value of each quintile. I bars represent 95% confidence intervals.